FROMLIST: video: rmk's HDMI notification prototype

FROMLIST: video: rmk's HDMI notification prototype

This is Russell's HDMI notification prototype [1], currently waiting
for the HDMI CEC situation to resolve.

The use case for the notifications on MediaTek MT8173 is to let the
(dis)connection notifications control an ALSA jack object.

No Signed-off-by since this is not my code, and still up for discussion.

[1] https://patchwork.kernel.org/patch/8351501/

(am from https://patchwork.kernel.org/patch/8887261/)

Signed-off-by: Chris Zhong <zyw@rock-chips.com>
Change-Id: I87daa156de6cfa7ff8db9df9d8ecc8c42d76798f